Jan, and CRs:
I think that the "just right" adjustment on NOS Campy hubs is done to help the wheelbuilding process. A too-tight-to-ride bearing adjustment prevents the rim shaking around when truing up a newly built wheel.
I've also found that when a new wheel is tensioned up, the hub bearing adjustment gets looser. I think that this is because the circumferential pressure on the inside bearing cup is decreased.
Andrew Gillis (Long Beach, CA, where the evening for is rolling in)